[MD Extensions] Add a details subpage, move to one list

chrome/browser/resources/md_extensions/item_list.css

Index: chrome/browser/resources/md_extensions/item_list.css
diff --git a/chrome/browser/resources/md_extensions/item_list.css b/chrome/browser/resources/md_extensions/item_list.css
index 9163291f92bdfa5d2c1a11bfd1548ce50a9f7baa..4976e2bb4fbaa907b0e1ecaeed1fb8206d5b095a 100644
--- a/chrome/browser/resources/md_extensions/item_list.css
+++ b/chrome/browser/resources/md_extensions/item_list.css
@@ -2,6 +2,10 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
+:host {
+  @apply(--layout-vertical);
+}
+
 h2 {
   color: #5a5a5a;
   font-size: 1.1em;
@@ -10,6 +14,10 @@ h2 {
   margin-top: 30px;
 }
 
+iron-list {
+  @apply(--layout-flex);
+}
+
 .wrapper {
   padding: 10px 0;
 }